Help ...... I broke my knife .

B

biker bo

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Mar 10, 2015
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cUjMWx.jpg


I used a Simmonds lathe file for this knife. It broke when I tried to straighten it after tempering it at 400° for an hour.

Does the grain structure look ok for using as a knife

Thanks ........ I also use 5160 and O1 but like the looks of rasp and file knifes.
 
Looks like there was an existing crack. Did you forge it from the file?
 
I did stock Removal. The spine has file work with holes drilled into it for copper wire. I HT then quenched in used motor oil . didn't like the file test so I HT again and this time I quenched in water.
I noticed the blade had a slight warp. I pulled it from the oven after an hour at 400° and tried to straighten it.

I don't know if the grain structure looks ok for the way I heat treated it . would it make a good knife .
 
Can we get a better photo? Yours seems to be focused on fingers and the blade is blurry and overexposed.
I agree with Rick re: previous crack, maybe due to stress concentration from file work and hole drilled in the spine.
 
The combination of file work, holes, and a water quench all lead up to a broken blade. The holes and grooves lead to a stress riser which formed a crack into the blade. That broke when the very brittle steel was bent.

Using a regular knife steel, like 1084, would have been a better choice. Files are pretty brittle, and a water quench is pretty brutal.


Also, try canola oil. Motor oil is a poor quenchant.
 
Thanks Stacy . I have some 5160 that I'm going to use for my next knife . If i don't send it out for heat treat I'll be using canola oil to quench.
 
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